Innovative Intersections and Interchanges

 

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Split Intersection icon
Innovative Intersection: Split Intersection
U.S. 1 in Old Town Alexandria, Va.

What Is A Split Intersection?

  • It divides traffic on a major street into two one-way streets that meet the side street at separate signalized intersections
  • It is similar to a traditional diamond interchange without grade-separated roadways

When Should It Be Considered?

  • At congested suburban intersections with heavy left-turn traffic volumes
  • In urban areas where two-way streets can be converted to one-way streets
  • Where grade-separation may be necessary in the future

Benefits

  • Improved safety: Reduces and spreads out the number of points where vehicles, pedestrians and bicyclists may cross paths
  • Increased efficiency: Separating traffic flow on major street allows the intersection to handle a greater volume of traffic and operate with less delay
  • Better synchronization: Corridor travel times are improved on both the major and side streets through synchronization of the two signalized intersections
  • Shorter wait times: Fewer traffic signal phases means less time stopping at the intersections

How to Navigate

Below shows how to navigate a split intersection. Click the image to view a larger version.

Center Turn Overpass navigation diagram

Conflict Points

The number of conflict points (locations where vehicle travel paths intersect) is one metric that can be used to evaluate the safety of an innovative intersection or interchange.

There are three categories: crossing, merging or diverging.

In general, merging and diverging conflict points — where vehicles move in the same direction — are associated with less severe crash types than crossing conflict points where vehicles are moving in opposite directions.

The diagrams below compare possible vehicle travel movements and associated conflict points at a conventional four-leg intersection to a split intersection.

These diagrams represent a general case, with one travel lane in each direction, and do not take into account pedestrian or bicycle movements at an intersection or interchange.

When compared to a conventional four-leg intersection, a split intersection has six fewer crossing conflict points.

Conventional Intersection: Conflict Points

Conventional Intersection conflict diagram.

Legend

Diagram Legend. Filled circle is diverging, half-filled is merging, empty is crossing.
Conflict Type Count
Crossing 16
Merging 8
Diverging 8
Total:

32 Conflicts

Split Intersection: Conflict Points

Split Intersection conflict diagram.

Legend

Diagram Legend. Filled circle is diverging, half-filled is merging, empty is crossing.
Conflict Type Count
Crossing 10
Merging 8
Diverging 8
Total:

26 Conflicts

Resources

Virginia Department of Transportation

Federal Highway Administration




Page last modified: Nov. 7, 2019